Koch's Postulates

Koch's postulates, also known as Henle-Koch postulates, were published by Robert Koch in various forms between 1878 and 1884 to set forth a method of demonstrating that a bacillus causes a particular disease. These postulates follow the process that Koch went through in demonstrating that anthrax and tuberculosis bacilli cause disease. Koch's postulates state that, to establish that an organism causes disease,

• the organism must be present in all cases of the disease;
• the organism must be grown in pure culture outside a diseased animal;
• when inoculated with the organism, healthy test animals must develop the same symptoms as were present in the original cases; and
• the organism must be present in the experimentally infected animals.

Koch believed that satisfying these postulates provided definitive proof that the organism was a ...